With the rapid development of Internet, especially with the rise of new services such as Internet Protocol Television (IPTV), the problem of Last Mile Access of terminal users becomes a bottleneck of the development of new services. The current predominant access technology, Asymmetrical Digital Subscriber Loop (ADSL), cannot provide a sufficient bandwidth. Therefore, at present, a study is made on technologies such as Very High Bit-Rate Digital Subscriber Loop (VDSL) and ADSL2+ (ITU Standard G.992.5) to solve the above problem. But these new technologies are still not mature enough, the cost per user for the commercial application is still very high, thus service providers dare not employ the technologies hastily. Therefore, the ADSL access is still predominant in the current broadband access market.
The Ethernet technology is very mature, and as the techniques of chip manufacturers develop rapidly, the transmission distance is increased greatly, so new opportunities are brought to the application of Ethernet to the broadband access. FIG. 1 shows the typical structure of an Ethernet access system used for a terminal user to access a broadband network in the prior art, wherein layer-2 switch 810 is used as an access equipment, layer-3 switch 820 is used as a gateway, and an access terminal accesses gateway 820 via layer-2 switch 810. Layer-2 switch 810 performs the layer-2 forwarding between a user and gateway 820, and the layer-2 isolation is accomplished between access terminals. Other operations, such as Quality of Service (QoS), may be accomplished at gateway 820.
In the field of the broadband access, average bandwidth of each user is low. For example, a bandwidth of 10 M may meet over 80% of the broadband access applications. However, the bandwidth of Ethernet products, such as Media Access Control (MAC) chip and long-distance transmission medium, has been developed to 1 G and 10 G to meet the requirement of enterprise network applications, and the price is considerably advantageous with respect to the bandwidth. But a lot of bandwidth will be wasted if the products are directly applied to the broadband access. Referring to FIG. 1, the equipment cost on the user side is still very high, and service providers cannot lower the access equipment cost per user when the network is disposed based on the solution. Moreover, in the current application, service providers need to dispose a lot of layer-2 switches at a position nearest to the user side. To guarantee that an access service can be activated to each possible user when the user needs to access an Internet service, these layer-2 switches usually have an access capacity of tens of ports, the number of the ports being usually equivalent to or even larger than that of the families nearby. But the access activation rate is usually very low, and is usually less than 10 families in a building. Thus, the cost of a layer-2 Ethernet switch will be laid on several users. Apparently, the cost will be too high. This is one of the key reasons why the mature Ethernet technologies cannot be widely used in Internet access applications.
It is a problem concerned by service providers that how to lower the cost of Ethernet access equipment. For equipment providers, because the market of Ethernet has been rather mature and the prices of various commercial chips cannot be lowered greatly, other approaches must be found to lower the cost of the equipment.
IBM simplifies the Ethernet switch to a certain extent by novelly using the multiplex technology. For details, reference may be made to US Patent Publication No. 20010050921 filed by IBM, in which a method for realizing a physical layer TDM is disclosed. In the method, signals input to several low-speed physical ports on a physical layer chip within a certain time period are collected circularly and multiplexed into a high-speed digital signal on one channel, and then the high-speed digital signal is transmitted to an MAC chip for layer-2 processing; which is opposite to the processing for digital signals output from the MAC chip. Therefore, the overall cost may be lowered correspondingly by lowering the number of MAC chips in the Ethernet switch and substituting a 100 M/GE MAC chip for a plurality of 10 M/100 M MAC chips.
The difference between the Ethernet multiplex technology disclosed in the patent application and the conventional Ethernet-related multiplex technology lies in that, the multiplex technology disclosed in the patent application intends to solve the problem of internal simplification of Ethernet switch, on the other hand, other Ethernet technologies intend to solve the problem of the high cost of the Ethernet transmission physical link or the problem that data cannot be directly output from a 10 GE physical channel because the equipment does not support 10 GE data processing capability. For example, 10 GE channels are multiplexed via a multiplex device, to one 10 GE channel for transmission, and the corresponding GE channels are demultiplexed and recovered on the other end.
This patent application submitted by IBM may solve the problem of Ethernet equipment simplification to a certain extent. Therefore, the reliability of the equipment may be improved and the overall cost of the equipment may be lowered.
If the technology is applied to the broadband access, the problem of the high cost of service providers may be released to a certain degree. However, the optimization effect is limited, because the access equipment has many MAC layers and upper-layer functional chipsets according to the prior art. Therefore, to make Ethernet broadband access become the predominant access approach, the overall cost of the access equipment should be further lowered.